1. Field of the Invention
This invention relates generally to log bunks, which are the U-shaped supports for holding logs on a tractor-trailer for over-the-road transportation. More specifically, the invention relates to a replacement for the bunk-pins, which prevent the log bunk from swiveling relative to the tractor or trailer during loading or unloading of the logs.
2. Related Art
Many logging trucks comprise a tractor-trailer combination, in which the tractor and the trailer each include a log bunk system for receiving the logs. As defined in this document, each log bunk system includes a U-shaped bunk, a generally horizontal bridge to which the bunk is connected, and bunk-ears. The bridge of the tractor bunk system is usually removably connected to the rear of the tractor and the bridge of the trailer bunk system is usually connected to the trailer above the trailer wheels. Each log bunk has a horizontal cross-bar with two upright arms upending from the cross-bar. Each bunk is rotationally connected to its respective bridge in such a way that the bunk can swivel, relative to the stationary bridge, around the center of the cross-bar, with the cross-bar rotating around its center in a horizontal plane. Each bunk swivels independently.
The trailer includes a long bar member, called a reach, which extends forward from the trailer bunk system for being hitched to, or otherwise connected to, the rear of the tractor. The reach typically includes a piston or spring system to allow some lengthening and shortening of the reach during operation of the logging truck.
When logs are loaded onto the tractor-trailer, they are stacked with one end resting in the tractor bunk and the other end resting in the trailer bunk. Bunk-pins are used to prevent the bunks from swiveling during log loading and consequently interfering with safe and efficient loading. Bunk-pins (BP) are inserted through the bunk-ears, as illustrated in FIG. 1 and 3. One bunk-ear extends from the bottom region of the bunk and one bunk-ear extends from the upper region of the corresponding bridge. When a bunk is positioned to be perpendicular to the longitudinal axis of the trailer or tractor, then the holes in the two bunk-ears align with each other and can receive a bunk-pin through both holes, thus, holding the bunk in place and preventing swiveling relative to the bridge.
As logs are loaded, they provide rigidity to the system because they themselves are rigid and they extend through both bunks. Once the logs are loaded, the bunk-pins may then be removed, because the logs form a rigid unit and keep the two bunks of the truck parallel to each other. Once the logs are loaded, the bunk-pins should be removed to allow the small amount of movement of the bunks that can occur when a load of logs settles and to allow the bunks to swivel during the travel of the truck on the road. The tractor bunk, especially, must swivel during travel, because the tractor steers the truck into a turn by turning relative to the log load and therefore relative to the tractor bunk. The trailer bunk also swivels, to a lesser degree than the tractor bunk, keeping steering and cornering safe and lessening the stress placed on the rear of the trailer.
Preferably, therefore, the bunk-pins are removed from the bunk-ears after log loading and are placed in a holder near the bunk-ears for easy access at the truck's destination for replacement in the bunk-ears before log unloading. When the bunk-pins are mistakenly left in the bunk-ears during travel, the bunk-pins are often severely bent or the bunk-ears are torn, requiring replacement of bunk-pins or welding and/or repair of the bunk-ears.